This Data Brief (PDF version available here) presents an analysis of excess mortality (increase in deaths) for California in 2020, using California vital statistics death data (death certificates), and includes assessment of differential increases by race/ethnic group, age, and increases in deaths due to conditions other than COVID-19. This analysis is a follow-up to findings in the 2020 State of Public Health Report, part of the State Health Assessment.

Summary



Findings

Deaths increased in 2020 compared to prior years

  • There were 316,945 deaths in California in 2020 (corresponding to an age-adjusted all-cause death rate of 675.4 per 100,000 population), compared to 267,034 deaths in 2019 (rate of 583.1). This is a 15.8% increase in the death rate in California, and is the highest statewide death rate in the past 12 years.

Table 1 - Number, Age-Adjusted Rate, and Increase in Rate from Prior Year, Deaths from All Causes in California, 2017-2020



  • As the pandemic intensified throughout 2020, the increases in the rates accelerated. Comparing the 1st quarter of 2020 to the 1st quarter of 2019, death rates were similar, with just a 0.4% increase; then, comparing 2nd quarters, there was a 10.2% increase; comparing 3rd quarters, a 23.1% increase; and when comparing 4th quarters, a 30.8% increase.

  • The rate in the 1st quarter of 2021 (Q1-2021) was higher than all quarterly rates in 2020, and much higher than any other recent prior quarter.

Figure 1 - All-Cause Death Rate by Quarter and Year, California 2017-2020 and Q1-2021

Multi-line trend chart with one line for each year, 2017 to 2020; trend in all-cause age-adjusted death rate in California by quarter. This chart highlights the important seasonal pattern in deaths, and the increase in deaths in 2020 compared to the prior 3 years.

Download Figure 1 Data



Deaths increased more among some race/ethnicity groups than others

  • From 2019 to 2020, the death rate increased 34.3% among Latinos, 7.6% among Whites, and about 20% among other groups.

Figure 2 - Percentage Increase in Race-Specific Age-Adjusted Death Rates 2019 to 2020

Bar chart; bars show percent increase in age-adjusted death rate for each race/ethnicity in California. This chart highlights disparities in the increases in deaths in 2020.

Download Figure 2 Data



  • Deaths among all race/ethnic groups were higher in quarters 2, 3, and 4 of 2020 compared to the average rate of the corresponding 2017-2019 quarters. As the year progressed, these differences within each race/ethnic group increased for all race/ethnic groups, and disparities in rates between groups increased.

  • These disparities are seen in Figure 3a by observing the increasing gap within any specific race/ethnicity group (dotted line compared to solid line), and by observing the increasingly larger gaps in some groups than others.

  • These increases are all statistically significant for all groups. (See Appendix Figure Set 1)

  • Rates continued to increase substantially for all race/ethnic groups in Q1-2021. In Q1-2021, the Latino rate surpassed the AI/AN rate.

Figure 3b - Percentage Increase in Age-Adjusted Death Rate by Quarter, 2020/Q1-2021 and 2017-2019 Average, by Race/Ethnicity

Grouped bar chart; groups are quarter 1 to 4 for each race/ethnic group, showing percentage increase in age-adjusted death rate from average rate of 2017 to 2019 to 2020; This chart highlights differences in deaths rates within and between race/ethnic groups as 2020 progressed.

Download Figure 3b Data



Causes of death other than COVID-19 also increased

  • Aside from COVID-19, three conditions with large percent increases in deaths from 2019 to 2020 were drug overdose (47.2%), homicide (32.8%), and diabetes (17.7%), Table 2.

  • The conditions with the largest absolute increases in number of deaths from 2019 to 2020 were Alzheimer’s disease and other dementias (3,623), ischemic heart disease (2,778), and drug overdoses (2,748).

  • For drug overdose deaths, the increases are consistent with recent trends, albeit accelerated. For Alzheimer’s disease and other dementias, the increases are consistent with long-term increasing trends, but a sharp reversal of decreasing trends the past two years. But for ischemic heart disease, the leading cause of death in California, the apparent increase is a concerning reversal of a steady downward trend of many prior years. The increase in homicide is also striking and alarming, in contrast to the encouraging decreases the last few years, and the long-term downward trend. (For long-term trends in cause-specific deaths in California, see Appendix Figure Set 2 or the California Community Burden of Disease Engine (CCB).)

  • Regarding decreases from 2019 to 2020, suicide/self-harm and lung cancers both had noteworthy decreases.

Table 2 - 2017 to 2020, Selected Causes of Death, ordered by percent increase 2019 to 2020 [note: table is sortable]



  • Figure 4 below shows 2017-2020 quarterly trends in conditions that had large percentage or large absolute increases from 2019 to 2020 (detailed data in Appendix Table 1).

  • As noted above, homicide deaths increased substantially in 2020, and strikingly by quarter. Homicide rates increased 23% in the 2nd quarter, 45% in the 3rd quarter and 58% in the 4th quarter 2020 compared to respective quarters in 2019.

  • COVID-19 emerged in early 2020 and deaths increased rapidly not only in California, but almost everywhere, as a massive global pandemic. In the 4th quarter of 2020 and 1st quarter of 2021, COVID-19 was, by far, the leading cause of death in California.


Figure 4 - Quarterly Trend in Selected Causes of Death 2017-2020/Q1-2021

Two panel multi-line charts; quarterly trends in selected causes of death from 2017 to 2020, with first panel on log scale and second panel on arithmetic scale. This chart shows the rapid increase in COVID-19 deaths and the increases in other causes of death.

Download Figure 4 Data




The amount of increase in deaths, and conditions associated with the increase, differed substantially by age and race/ethnicity

  • In general, a large proportion of the increase in deaths among older persons was due to COVID-19 while a large proportion of the increase in deaths among younger persons was due to other conditions.

  • As seen in Figure 5, the greatest percentage increases in the number of deaths were among older Latinos, younger Blacks, and 35-44 year-old AI/AN (detailed data in Appendix Figure Set 3 and Appendix Table 2).

  • The striking increases among Blacks ages 5-14 and 15-24 are particularly concerning for a range of reasons. It is also important to note that these large percentage increases among young persons represent a smaller total number of deaths than among older persons.

  • Of the 465 deaths (an increase of 156 deaths) among 15-24 year old Blacks in 2020, the greatest contributing causes were homicide, road injury, and drug overdose. Specifically, 138 (increase of 23 deaths) were due to homicides, 85 (increase of 31) to road injury, 76 (increase of 42) to drug overdoses, and 18 (increase of 8) to “ill-defined” conditions, some of which will be clarified in the coming months. These concerns are of course not restricted to just one race/ethnic group. For example, these same causes were leading contributors to the 1,966 deaths among Latinos aged 15-24 in 2020. Specifically, 467 (increase of 242 deaths) were due to drug overdoses, 333 (increase of 84) to homicide, 418 (increase of 71) to road injury, as well as 61 (increase of 33) to “ill-defined” conditions and to COVID-19. These cause-specific data by race/ethnicity and age are available in Appendix Table 3.

  • Of the 106 deaths (an increase of 46 deaths) among 35-44 year old AI/AN in 2020, the greatest contributing causes were drug overdose, 22 (increase of 14 deaths) and road injury, 11 (increase of 6).


Figure 5 - Percent Increase in Number of Deaths 2019 to 2020 by Age Group and Race/Ethnicity and Proportion of Increase due to COVID-19

Complex multi-panel horizontal stacked bar chart; shows percent increase in number of deaths by age group, with stacked bars representing deaths from COVID-19 versus all other causes, and panels for each race/ethnic group. This chart highlights important differences in increases in deaths by age, and by race, and that the cause of increases (COVID-19 versus other causes) differs by age.

Note: The “cause index” is, rather than a direct proportion, the ratio of the number of COVID-19 deaths in 2020 to the total increase in deaths from 2019 to 2020, and is truncated at 1.0. See the Methods section for details.
*For younger NH/PI and AI/AN age groups, the underlying number of deaths for 2019 and/or 2020 is <25 so data are not shown
**25-34 year old AI/AN experienced an overall decrease in deaths, and had a small number of deaths from COVID-19

Download Figure 5 Data



Data, Methods, and Technical Notes

Discussion



Additional Exploratory Analyses

Social Determinants of Health

  • Excess mortality was associated with Social Determinants of Health, including Poverty, House Overcrowding, and Limited English Proficiency, in preliminary/exploratory analyses
  • SDOH are based on the community level (census tract) not individual level, using the Krieger/Harvard Public Health Disparities Geocoding approach
  • Both SDOH and race/ethnicity are independently associated with excess mortality. The patterns of SDOH and excess mortality different across r/e groups. These interrelationships are complex, difficulty to measure, and important.

Figure 7 - Increase in Death Rate by Race/Ethnicity, and Social Determinants of Health in 2020



Different calculation methods can yield different insights into the magnitude and disparities of excess mortality

  • In the information above, excess mortality is calculated as the percent increase in a rate from 2019 to 2020. Other methods can be used, including a method that calculates excess mortality as the increase in the number of death divided by the population size – this method has been used in a published letter assessing excess mortality in California.

  • Part A in the chart below replicates Figure 2 above, and indicates that Latinos have the highest excess mortality based on percent increase. Part B below uses the other method and indicates that Blacks have the highest excess mortality based on the “excess mortality rate”; and indicates that both American Indian/Alaska Natives and Native Hawaiian/Pacific Islanders have a higher excess mortality rate than Latinos.

  • The “conclusions” from the two methods differ because of the different ways the methods take into account the rate in the baseline period and the population size. Both of these methods are reasonable and provide different insights.

Figure 8 - Excess Mortality Measures Comparison



Disaggregation of race and ethnicity into more detailed groups provides further insight


  • This preliminary analysis looks at excess mortality using disaggregation of broad race and ethnicity into detailed groups. This type of work is important since detailed race and ethnicity “sub-groups” are likely to be heterogeneous with respect to many characteristics, including health outcomes, health care access and health-related behaviors, and upstream social determinants of health. Analysis based on these more specific “sub-groups” can inform different strategies in terms of public health programs and interventions.


  • Key observations in this chart:
    • There is substantial heterogeneity in excess mortality within in the broad Latino, Asian, and Pacific Islander groups. For example,
      • Among Latinos the “Other Hispanic” group appears to have the highest excess mortality, whereas Puerto Ricans and Cubans appear to have the lowest excess mortality.
        • Note that for deaths the “Other Hispanic” group cannot be disaggregated. But among the population data, 62% of this group is Central American—this strongly suggests that a majority of deaths in this group are also Central Americans, and that Central Americans have very high excess mortality.
      • Among Asians, Cambodians appear to have high excess mortality whereas Thais appear to have low excess mortality.
    • There appears to be notably high excess mortality among the “Other Hispanics” and Guamanian sub-groups.
      • The excess mortality being high in these two groups based on both the “Percent Increase” and “Excess Mortality Rate” approaches strengthens the evidence for this observation.


  • This “first look” at these detailed data has a number of limitations:
    • The “percent increase” excess mortality here uses crude rates, not age-adjusted rates as elsewhere in this Brief.
    • There are differences in collection of race/ethnicity information for deaths (family or MD informant) versus population data (self-report via survey), which likely contribute to some numerator/denominator misalignment.
    • There are some differences in race/ethnicity groupings and codes between death and population data. Some minor assumptions were required about mapping to a common list for purposes of this analysis.
    • The population data (2015-2019, American Community Survey) are not quite as current as the death data (2019 and 2020).
    • Some of the subgroup numbers are small and may be unstable. Please note that the increase in the number of deaths from 2019 to 2020 for each group is shown inside the bars below.


Figure 9 - Excess Mortality Based on Detailed Race and Ethnicity Groupings (using both “Percent Increase” and “Excess Mortality Rate” Approaches)1

NOTES:

  1. The population denominator data source for these detailed race and ethnicity groupings is the American Community Survey, 2015-2019 release. Population denominator data used elsewhere in this Brief are from the California Department of Finance (DOF)–the DOF source does not provide detailed race/ethnicity disaggregation.
  2. Based on the population data source the “Other Hispanics” category is 62% Central American. Current California death data includes codes for “Mexican”, “Cuban”, “Puerto Rican”, and “Other Hispanic”. Modifications are underway to the death data system, and more detailed data are expected in 2022.
  3. “Asian Multiple” includes persons of more than one “detailed” Asian race, but not “Asian Unknown”, and no other races, and not Hispanic.
  4. “Multirace” includes persons of more than one race group, but not “Other”, and not Hispanic.
  5. “Pac. Isl. Oth./Mult.” includes persons of another “detailed” Pacific Islander race or of more than one “detailed” Pacific Islander race, and no other races, and not Hispanic.
  6. “Other” person indicating another race without specifying what race.



Figure 10 - Distribution of California Population by Grouped Race/Ethnicity and by Detailed Race/Ethnicity




Conclusion